为什么 android:requestLegacyExternalStorage=“true” 在 Android 10 - API 29 中不起作用

Question

I have migrated my project compileSdkVersion from 28 to 29 and add android:requestLegacyExternalStorage="true" in my manifest, but file operations like downloading and file opening not working as it is in SDK 28

gradle file

compileSdkVersion 29

defaultConfig {
    applicationId "in.example.app"
    minSdkVersion 21
    targetSdkVersion 29
    versionCode 90
    versionName "1.8.3"

    testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
}

Manifest file

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
package="in.example.app">

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.VIBRATE" />
<uses-permission android:name="android.permission.SMS_FINANCIAL_TRANSACTIONS" />

<application
    android:name=".MyApp"
    android:allowBackup="true"
    android:hardwareAccelerated="true"
    android:icon="@mipmap/ic_launcher"
    android:largeHeap="true"
    android:networkSecurityConfig="@xml/network_security_config"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme"
    tools:replace="android:theme,android:allowBackup"
    tools:targetApi="n"
    android:requestLegacyExternalStorage="true">

    <activity android:name=".ui.main.MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.DEFAULT" />
        </intent-filter>
    </activity>

    <provider
        android:name="androidx.core.content.FileProvider"
        android:authorities="in.example.app.fileprovider"
        android:exported="false"
        android:grantUriPermissions="true">
        <meta-data
            android:name="android.support.FILE_PROVIDER_PATHS"
            android:resource="@xml/provider_paths" />
    </provider>

</application>

file downloading code

fun startDownloading(path: String, url: String): Long {
    return try {
        val downFileName = re.replace(url.substringAfterLast("/"), "")

        val downloadManager = context.getSystemService(DOWNLOAD_SERVICE) as DownloadManager
        val request = DownloadManager.Request(Uri.parse(url))
            request.setTitle(downFileName)
                .setDestinationInExternalPublicDir(path, downFileName)
                .setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED)
        downloadManager.enqueue(request)
    } catch (e: Exception){
        0
    }
}

• path should be a folder location in internal storage "/myapp/study materials/"
• url should be a file location url from the server

opening a file

fun openFile(title: String, path: String){
    try {
        val newFile = File(Environment.getExternalStorageDirectory().absolutePath + path, title)

        val uri = if (Build.VERSION.SDK_INT > Build.VERSION_CODES.M)
        {
            FileProvider.getUriForFile(context, BuildConfig.APPLICATION_ID + ".fileprovider", newFile)
        } else{
            Uri.fromFile(newFile)
        }

        val intent = Intent(Intent.ACTION_VIEW, uri)
        intent.setDataAndType(uri, context.contentResolver.getType(uri))
        intent.flags = Intent.FLAG_ACTIVITY_CLEAR_TOP
        intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
        val activities: List<ResolveInfo> = context.packageManager.queryIntentActivities(intent, 0)
        val isIntentSafe: Boolean = activities.isNotEmpty()

        // Start an activity if it's safe
        if (isIntentSafe) {
            context.startActivity(Intent.createChooser(intent, "Open With"))
        } else{
            MDToast.makeText(context, "No Application Found For Opening This File", MDToast.TYPE_INFO).show()
        }
    } catch (e : Exception){
        println("=============== ${e.message}")
    }

}

• path should be a folder location in internal storage "/myapp/study materials/"
• title should be the file name

file existance checking

override fun checkFileExistence(title: String, path: String): Boolean {
    var flag = false
    try {
        val direct = File(
            Environment.getExternalStorageDirectory().toString()
                    + path + title)
        flag = direct.exists()
    } catch (e: Exception) {
    }

    return flag
}

• path should be a folder location in internal storage "/myapp/study materials/"
• title should be the file name

I have added all code that is not working while updating to SDK 29, I want to download a file from the server and save it to an app-specific folder in internal storage also need to check if the file is already downloaded or not before downloading it. if it is already downloaded I need to open that file

Answer 1

I had similar issues to those mentioned here. I found out that on Android 10, I have to check WRITE_EXTERNAL_STORAGE even when file is already downloaded and I just need to open it.

if (ContextCompat.checkSelfPermission(this, WRITE_EXTERNAL_STORAGE) != PERMISSION_GRANTED) {
    ActivityCompat.requestPermissions(this, arrayOf(WRITE_EXTERNAL_STORAGE), 100)
}

Adding the check before any manipulation with the file fixed the "There was a problem parsing the package" error when opening the APK file.

EDIT:

I also found another (probably better) solution. Instead of using external public storage , I switched to external storage of the app:

downloadRequest.setDestinationInExternalFilesDir(...)

and to access the file use

new File(context.getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS), mFileName);

instead of now deprecated Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)

As a bonus there's no need to use android:requestLegacyExternalStorage="true" in AndroidManifest.